Exercise 0.A - The three day interruption log
Run the log across three consecutive working days. Do not choose a quiet week, and do not restart because a day went badly, because the days that go badly are the ones with the information in them.
Record five fields per entry: arrival time, named source, what it displaced, minutes spent, and whether you returned to the displaced work and how much later. At the end of each day, classify every entry as necessary, useful but poorly timed, unnecessary, avoidable, or self created.
You are finished when you have three complete days, a count by source, and a total of minutes displaced from each of your two or three stated priorities.
This exercise fails in two ways. The first is logging only what other people sent you, which leaves the self created column near-empty and removes the one category you control unilaterally. The second is reconstructing entries at the end of the day, which produces a document that agrees with your memory, which is the document you already had.